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                    接口类型
            
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                    示例: 表达式求值
            
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                    类型断言
            
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                    基于类型断言识别错误类型
            
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                    通过类型断言查询接口
            
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                    类型分支
            
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                    示例: 基于标记的XML解码
            
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                    补充几点
            
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                    Goroutines
            
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                    示例: 并发的Clock服务
            
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                    示例: 并发的Echo服务
            
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                    Channels
            
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                    并发的循环
            
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                    示例: 并发的Web爬虫
            
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                    基于select的多路复用
            
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                    示例: 并发的目录遍历
            
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                    并发的退出
            
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                    示例: 聊天服务
            
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                    基于共享变量的并发
            
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                    竞争条件
            
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                    sync.Mutex互斥锁
            
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                    sync.RWMutex读写锁
            
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                    内存同步
            
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                    sync.Once惰性初始化
            
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                    竞争条件检测
            
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        <li class="chapter " data-level="1.10.7" data-path="../ch9/ch9-07.html">
            
                <a href="../ch9/ch9-07.html">
            
                    
                    示例: 并发的非阻塞缓存
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.10.8" data-path="../ch9/ch9-08.html">
            
                <a href="../ch9/ch9-08.html">
            
                    
                    Goroutines和线程
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.11" data-path="../ch10/ch10.html">
            
                <a href="../ch10/ch10.html">
            
                    
                    包和工具
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.11.1" data-path="../ch10/ch10-01.html">
            
                <a href="../ch10/ch10-01.html">
            
                    
                    包简介
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.2" data-path="../ch10/ch10-02.html">
            
                <a href="../ch10/ch10-02.html">
            
                    
                    导入路径
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.3" data-path="../ch10/ch10-03.html">
            
                <a href="../ch10/ch10-03.html">
            
                    
                    包声明
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.4" data-path="../ch10/ch10-04.html">
            
                <a href="../ch10/ch10-04.html">
            
                    
                    导入声明
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.5" data-path="../ch10/ch10-05.html">
            
                <a href="../ch10/ch10-05.html">
            
                    
                    包的匿名导入
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.6" data-path="../ch10/ch10-06.html">
            
                <a href="../ch10/ch10-06.html">
            
                    
                    包和命名
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.7" data-path="../ch10/ch10-07.html">
            
                <a href="../ch10/ch10-07.html">
            
                    
                    工具
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.12" data-path="../ch11/ch11.html">
            
                <a href="../ch11/ch11.html">
            
                    
                    测试
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.12.1" data-path="../ch11/ch11-01.html">
            
                <a href="../ch11/ch11-01.html">
            
                    
                    go test
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.2" data-path="../ch11/ch11-02.html">
            
                <a href="../ch11/ch11-02.html">
            
                    
                    测试函数
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.3" data-path="../ch11/ch11-03.html">
            
                <a href="../ch11/ch11-03.html">
            
                    
                    测试覆盖率
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.4" data-path="../ch11/ch11-04.html">
            
                <a href="../ch11/ch11-04.html">
            
                    
                    基准测试
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.5" data-path="../ch11/ch11-05.html">
            
                <a href="../ch11/ch11-05.html">
            
                    
                    剖析
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.6" data-path="../ch11/ch11-06.html">
            
                <a href="../ch11/ch11-06.html">
            
                    
                    示例函数
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.13" data-path="../ch12/ch12.html">
            
                <a href="../ch12/ch12.html">
            
                    
                    反射
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.13.1" data-path="../ch12/ch12-01.html">
            
                <a href="../ch12/ch12-01.html">
            
                    
                    为何需要反射?
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.2" data-path="../ch12/ch12-02.html">
            
                <a href="../ch12/ch12-02.html">
            
                    
                    reflect.Type和reflect.Value
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.3" data-path="../ch12/ch12-03.html">
            
                <a href="../ch12/ch12-03.html">
            
                    
                    Display递归打印
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.4" data-path="../ch12/ch12-04.html">
            
                <a href="../ch12/ch12-04.html">
            
                    
                    示例: 编码S表达式
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.5" data-path="../ch12/ch12-05.html">
            
                <a href="../ch12/ch12-05.html">
            
                    
                    通过reflect.Value修改值
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.6" data-path="../ch12/ch12-06.html">
            
                <a href="../ch12/ch12-06.html">
            
                    
                    示例: 解码S表达式
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.7" data-path="../ch12/ch12-07.html">
            
                <a href="../ch12/ch12-07.html">
            
                    
                    获取结构体字段标签
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.8" data-path="../ch12/ch12-08.html">
            
                <a href="../ch12/ch12-08.html">
            
                    
                    显示一个类型的方法集
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.9" data-path="../ch12/ch12-09.html">
            
                <a href="../ch12/ch12-09.html">
            
                    
                    几点忠告
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.14" data-path="../ch13/ch13.html">
            
                <a href="../ch13/ch13.html">
            
                    
                    底层编程
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.14.1" data-path="../ch13/ch13-01.html">
            
                <a href="../ch13/ch13-01.html">
            
                    
                    unsafe.Sizeof, Alignof 和 Offsetof
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.2" data-path="../ch13/ch13-02.html">
            
                <a href="../ch13/ch13-02.html">
            
                    
                    unsafe.Pointer
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.3" data-path="../ch13/ch13-03.html">
            
                <a href="../ch13/ch13-03.html">
            
                    
                    示例: 深度相等判断
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.4" data-path="../ch13/ch13-04.html">
            
                <a href="../ch13/ch13-04.html">
            
                    
                    通过cgo调用C代码
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.5" data-path="../ch13/ch13-05.html">
            
                <a href="../ch13/ch13-05.html">
            
                    
                    几点忠告
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.15" data-path="../appendix/appendix.html">
            
                <a href="../appendix/appendix.html">
            
                    
                    附录
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.15.1" data-path="../appendix/appendix-a-errata.html">
            
                <a href="../appendix/appendix-a-errata.html">
            
                    
                    附录A：原文勘误
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.15.2" data-path="../appendix/appendix-b-author.html">
            
                <a href="../appendix/appendix-b-author.html">
            
                    
                    附录B：作者译者
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.15.3" data-path="../appendix/appendix-c-cpoyright.html">
            
                <a href="../appendix/appendix-c-cpoyright.html">
            
                    
                    附录C：译文授权
            
                </a>
            

            
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        <li class="chapter " data-level="1.15.4" data-path="../appendix/appendix-d-translations.html">
            
                <a href="../appendix/appendix-d-translations.html">
            
                    
                    附录D：其它语言
            
                </a>
            

            
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                                <h2 id="711-&#x57FA;&#x4E8E;&#x7C7B;&#x578B;&#x65AD;&#x8A00;&#x533A;&#x522B;&#x9519;&#x8BEF;&#x7C7B;&#x578B;">7.11. &#x57FA;&#x4E8E;&#x7C7B;&#x578B;&#x65AD;&#x8A00;&#x533A;&#x522B;&#x9519;&#x8BEF;&#x7C7B;&#x578B;</h2>
<p>&#x601D;&#x8003;&#x5728;os&#x5305;&#x4E2D;&#x6587;&#x4EF6;&#x64CD;&#x4F5C;&#x8FD4;&#x56DE;&#x7684;&#x9519;&#x8BEF;&#x96C6;&#x5408;&#x3002;I/O&#x53EF;&#x4EE5;&#x56E0;&#x4E3A;&#x4EFB;&#x4F55;&#x6570;&#x91CF;&#x7684;&#x539F;&#x56E0;&#x5931;&#x8D25;&#xFF0C;&#x4F46;&#x662F;&#x6709;&#x4E09;&#x79CD;&#x7ECF;&#x5E38;&#x7684;&#x9519;&#x8BEF;&#x5FC5;&#x987B;&#x8FDB;&#x884C;&#x4E0D;&#x540C;&#x7684;&#x5904;&#x7406;&#xFF1A;&#x6587;&#x4EF6;&#x5DF2;&#x7ECF;&#x5B58;&#x5728;&#xFF08;&#x5BF9;&#x4E8E;&#x521B;&#x5EFA;&#x64CD;&#x4F5C;&#xFF09;&#xFF0C;&#x627E;&#x4E0D;&#x5230;&#x6587;&#x4EF6;&#xFF08;&#x5BF9;&#x4E8E;&#x8BFB;&#x53D6;&#x64CD;&#x4F5C;&#xFF09;&#xFF0C;&#x548C;&#x6743;&#x9650;&#x62D2;&#x7EDD;&#x3002;os&#x5305;&#x4E2D;&#x63D0;&#x4F9B;&#x4E86;&#x4E09;&#x4E2A;&#x5E2E;&#x52A9;&#x51FD;&#x6570;&#x6765;&#x5BF9;&#x7ED9;&#x5B9A;&#x7684;&#x9519;&#x8BEF;&#x503C;&#x8868;&#x793A;&#x7684;&#x5931;&#x8D25;&#x8FDB;&#x884C;&#x5206;&#x7C7B;&#xFF1A;</p>
<pre><code class="lang-go"><span class="hljs-keyword">package</span> os

<span class="hljs-keyword">func</span> IsExist(err error) <span class="hljs-keyword">bool</span>
<span class="hljs-keyword">func</span> IsNotExist(err error) <span class="hljs-keyword">bool</span>
<span class="hljs-keyword">func</span> IsPermission(err error) <span class="hljs-keyword">bool</span>
</code></pre>
<p>&#x5BF9;&#x8FD9;&#x4E9B;&#x5224;&#x65AD;&#x7684;&#x4E00;&#x4E2A;&#x7F3A;&#x4E4F;&#x7ECF;&#x9A8C;&#x7684;&#x5B9E;&#x73B0;&#x53EF;&#x80FD;&#x4F1A;&#x53BB;&#x68C0;&#x67E5;&#x9519;&#x8BEF;&#x6D88;&#x606F;&#x662F;&#x5426;&#x5305;&#x542B;&#x4E86;&#x7279;&#x5B9A;&#x7684;&#x5B50;&#x5B57;&#x7B26;&#x4E32;&#xFF0C;</p>
<pre><code class="lang-go"><span class="hljs-keyword">func</span> IsNotExist(err error) <span class="hljs-keyword">bool</span> {
    <span class="hljs-comment">// <span class="hljs-doctag">NOTE:</span> not robust!</span>
    <span class="hljs-keyword">return</span> strings.Contains(err.Error(), <span class="hljs-string">&quot;file does not exist&quot;</span>)
}
</code></pre>
<p>&#x4F46;&#x662F;&#x5904;&#x7406;I/O&#x9519;&#x8BEF;&#x7684;&#x903B;&#x8F91;&#x53EF;&#x80FD;&#x4E00;&#x4E2A;&#x548C;&#x53E6;&#x4E00;&#x4E2A;&#x5E73;&#x53F0;&#x975E;&#x5E38;&#x7684;&#x4E0D;&#x540C;&#xFF0C;&#x6240;&#x4EE5;&#x8FD9;&#x79CD;&#x65B9;&#x6848;&#x5E76;&#x4E0D;&#x5065;&#x58EE;&#xFF0C;&#x5E76;&#x4E14;&#x5BF9;&#x76F8;&#x540C;&#x7684;&#x5931;&#x8D25;&#x53EF;&#x80FD;&#x4F1A;&#x62A5;&#x51FA;&#x5404;&#x79CD;&#x4E0D;&#x540C;&#x7684;&#x9519;&#x8BEF;&#x6D88;&#x606F;&#x3002;&#x5728;&#x6D4B;&#x8BD5;&#x7684;&#x8FC7;&#x7A0B;&#x4E2D;&#xFF0C;&#x901A;&#x8FC7;&#x68C0;&#x67E5;&#x9519;&#x8BEF;&#x6D88;&#x606F;&#x7684;&#x5B50;&#x5B57;&#x7B26;&#x4E32;&#x6765;&#x4FDD;&#x8BC1;&#x7279;&#x5B9A;&#x7684;&#x51FD;&#x6570;&#x4EE5;&#x671F;&#x671B;&#x7684;&#x65B9;&#x5F0F;&#x5931;&#x8D25;&#x662F;&#x975E;&#x5E38;&#x6709;&#x7528;&#x7684;&#xFF0C;&#x4F46;&#x5BF9;&#x4E8E;&#x7EBF;&#x4E0A;&#x7684;&#x4EE3;&#x7801;&#x662F;&#x4E0D;&#x591F;&#x7684;&#x3002;</p>
<p>&#x4E00;&#x4E2A;&#x66F4;&#x53EF;&#x9760;&#x7684;&#x65B9;&#x5F0F;&#x662F;&#x4F7F;&#x7528;&#x4E00;&#x4E2A;&#x4E13;&#x95E8;&#x7684;&#x7C7B;&#x578B;&#x6765;&#x63CF;&#x8FF0;&#x7ED3;&#x6784;&#x5316;&#x7684;&#x9519;&#x8BEF;&#x3002;os&#x5305;&#x4E2D;&#x5B9A;&#x4E49;&#x4E86;&#x4E00;&#x4E2A;PathError&#x7C7B;&#x578B;&#x6765;&#x63CF;&#x8FF0;&#x5728;&#x6587;&#x4EF6;&#x8DEF;&#x5F84;&#x64CD;&#x4F5C;&#x4E2D;&#x6D89;&#x53CA;&#x5230;&#x7684;&#x5931;&#x8D25;&#xFF0C;&#x50CF;Open&#x6216;&#x8005;Delete&#x64CD;&#x4F5C;&#xFF1B;&#x5E76;&#x4E14;&#x5B9A;&#x4E49;&#x4E86;&#x4E00;&#x4E2A;&#x53EB;LinkError&#x7684;&#x53D8;&#x4F53;&#x6765;&#x63CF;&#x8FF0;&#x6D89;&#x53CA;&#x5230;&#x4E24;&#x4E2A;&#x6587;&#x4EF6;&#x8DEF;&#x5F84;&#x7684;&#x64CD;&#x4F5C;&#xFF0C;&#x50CF;Symlink&#x548C;Rename&#x3002;&#x8FD9;&#x4E0B;&#x9762;&#x662F;os.PathError&#xFF1A;</p>
<pre><code class="lang-go"><span class="hljs-keyword">package</span> os

<span class="hljs-comment">// PathError records an error and the operation and file path that caused it.</span>
<span class="hljs-keyword">type</span> PathError <span class="hljs-keyword">struct</span> {
    Op   <span class="hljs-keyword">string</span>
    Path <span class="hljs-keyword">string</span>
    Err  error
}

<span class="hljs-keyword">func</span> (e *PathError) Error() <span class="hljs-keyword">string</span> {
    <span class="hljs-keyword">return</span> e.Op + <span class="hljs-string">&quot; &quot;</span> + e.Path + <span class="hljs-string">&quot;: &quot;</span> + e.Err.Error()
}
</code></pre>
<p>&#x5927;&#x591A;&#x6570;&#x8C03;&#x7528;&#x65B9;&#x90FD;&#x4E0D;&#x77E5;&#x9053;PathError&#x5E76;&#x4E14;&#x901A;&#x8FC7;&#x8C03;&#x7528;&#x9519;&#x8BEF;&#x672C;&#x8EAB;&#x7684;Error&#x65B9;&#x6CD5;&#x6765;&#x7EDF;&#x4E00;&#x5904;&#x7406;&#x6240;&#x6709;&#x7684;&#x9519;&#x8BEF;&#x3002;&#x5C3D;&#x7BA1;PathError&#x7684;Error&#x65B9;&#x6CD5;&#x7B80;&#x5355;&#x5730;&#x628A;&#x8FD9;&#x4E9B;&#x5B57;&#x6BB5;&#x8FDE;&#x63A5;&#x8D77;&#x6765;&#x751F;&#x6210;&#x9519;&#x8BEF;&#x6D88;&#x606F;&#xFF0C;PathError&#x7684;&#x7ED3;&#x6784;&#x4FDD;&#x62A4;&#x4E86;&#x5185;&#x90E8;&#x7684;&#x9519;&#x8BEF;&#x7EC4;&#x4EF6;&#x3002;&#x8C03;&#x7528;&#x65B9;&#x9700;&#x8981;&#x4F7F;&#x7528;&#x7C7B;&#x578B;&#x65AD;&#x8A00;&#x6765;&#x68C0;&#x6D4B;&#x9519;&#x8BEF;&#x7684;&#x5177;&#x4F53;&#x7C7B;&#x578B;&#x4EE5;&#x4FBF;&#x5C06;&#x4E00;&#x79CD;&#x5931;&#x8D25;&#x548C;&#x53E6;&#x4E00;&#x79CD;&#x533A;&#x5206;&#x5F00;&#xFF1B;&#x5177;&#x4F53;&#x7684;&#x7C7B;&#x578B;&#x53EF;&#x4EE5;&#x6BD4;&#x5B57;&#x7B26;&#x4E32;&#x63D0;&#x4F9B;&#x66F4;&#x591A;&#x7684;&#x7EC6;&#x8282;&#x3002;</p>
<pre><code class="lang-go">_, err := os.Open(<span class="hljs-string">&quot;/no/such/file&quot;</span>)
fmt.Println(err) <span class="hljs-comment">// &quot;open /no/such/file: No such file or directory&quot;</span>
fmt.Printf(<span class="hljs-string">&quot;%#v\n&quot;</span>, err)
<span class="hljs-comment">// Output:</span>
<span class="hljs-comment">// &amp;os.PathError{Op:&quot;open&quot;, Path:&quot;/no/such/file&quot;, Err:0x2}</span>
</code></pre>
<p>&#x8FD9;&#x5C31;&#x662F;&#x4E09;&#x4E2A;&#x5E2E;&#x52A9;&#x51FD;&#x6570;&#x662F;&#x600E;&#x4E48;&#x5DE5;&#x4F5C;&#x7684;&#x3002;&#x4F8B;&#x5982;&#x4E0B;&#x9762;&#x5C55;&#x793A;&#x7684;IsNotExist&#xFF0C;&#x5B83;&#x4F1A;&#x62A5;&#x51FA;&#x662F;&#x5426;&#x4E00;&#x4E2A;&#x9519;&#x8BEF;&#x548C;syscall.ENOENT&#xFF08;&#xA7;7.8&#xFF09;&#x6216;&#x8005;&#x548C;&#x6709;&#x540D;&#x7684;&#x9519;&#x8BEF;os.ErrNotExist&#x76F8;&#x7B49;&#xFF08;&#x53EF;&#x4EE5;&#x5728;&#xA7;5.4.2&#x4E2D;&#x627E;&#x5230;io.EOF&#xFF09;&#xFF1B;&#x6216;&#x8005;&#x662F;&#x4E00;&#x4E2A;<code>*PathError</code>&#xFF0C;&#x5B83;&#x5185;&#x90E8;&#x7684;&#x9519;&#x8BEF;&#x662F;syscall.ENOENT&#x548C;os.ErrNotExist&#x5176;&#x4E2D;&#x4E4B;&#x4E00;&#x3002;</p>
<pre><code class="lang-go"><span class="hljs-keyword">import</span> (
    <span class="hljs-string">&quot;errors&quot;</span>
    <span class="hljs-string">&quot;syscall&quot;</span>
)

<span class="hljs-keyword">var</span> ErrNotExist = errors.New(<span class="hljs-string">&quot;file does not exist&quot;</span>)

<span class="hljs-comment">// IsNotExist returns a boolean indicating whether the error is known to</span>
<span class="hljs-comment">// report that a file or directory does not exist. It is satisfied by</span>
<span class="hljs-comment">// ErrNotExist as well as some syscall errors.</span>
<span class="hljs-keyword">func</span> IsNotExist(err error) <span class="hljs-keyword">bool</span> {
    <span class="hljs-keyword">if</span> pe, ok := err.(*PathError); ok {
        err = pe.Err
    }
    <span class="hljs-keyword">return</span> err == syscall.ENOENT || err == ErrNotExist
}
</code></pre>
<p>&#x4E0B;&#x9762;&#x8FD9;&#x91CC;&#x662F;&#x5B83;&#x7684;&#x5B9E;&#x9645;&#x4F7F;&#x7528;&#xFF1A;</p>
<pre><code class="lang-go">_, err := os.Open(<span class="hljs-string">&quot;/no/such/file&quot;</span>)
fmt.Println(os.IsNotExist(err)) <span class="hljs-comment">// &quot;true&quot;</span>
</code></pre>
<p>&#x5982;&#x679C;&#x9519;&#x8BEF;&#x6D88;&#x606F;&#x7ED3;&#x5408;&#x6210;&#x4E00;&#x4E2A;&#x66F4;&#x5927;&#x7684;&#x5B57;&#x7B26;&#x4E32;&#xFF0C;&#x5F53;&#x7136;PathError&#x7684;&#x7ED3;&#x6784;&#x5C31;&#x4E0D;&#x518D;&#x4E3A;&#x4EBA;&#x6240;&#x77E5;&#xFF0C;&#x4F8B;&#x5982;&#x901A;&#x8FC7;&#x4E00;&#x4E2A;&#x5BF9;fmt.Errorf&#x51FD;&#x6570;&#x7684;&#x8C03;&#x7528;&#x3002;&#x533A;&#x522B;&#x9519;&#x8BEF;&#x901A;&#x5E38;&#x5FC5;&#x987B;&#x5728;&#x5931;&#x8D25;&#x64CD;&#x4F5C;&#x540E;&#xFF0C;&#x9519;&#x8BEF;&#x4F20;&#x56DE;&#x8C03;&#x7528;&#x8005;&#x524D;&#x8FDB;&#x884C;&#x3002;</p>

                                
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